/**
 * IdentityConstraintEngine  (G28b - v1.5.0)
 * ─────────────────────────────────────────
 * v1.7.0: Single-pass DOM evaluation of xs:key, xs:unique, and xs:keyref.
 *         Replaced recursive _walk with iterative post-order traversal to
 *         avoid call-stack overflow on deep documents.
 *         Replaced O(n) stack.shift()/unshift in _findDescendants with O(1)
 *         push/pop using reversed insertion order.
 *
 * XPath selector: `.`, `./child`, `.//descendant`, `//descendant`, `child::name`, `*`
 * Field expression: `@attr`, `child`, `.` (text content)
 * Composite multi-field keys: `fields: ['@a', '@b']`
 */
import { SchemaModel } from '../schema/SchemaModel';
import { XmlDocument } from '../parser/XmlNodes';
import { ValidationResult } from './ValidationResult';
export declare class IdentityConstraintEngine {
    private schema;
    /** P0 fix: pre-built set of element names that own identity constraints.
     *  Avoids two Map.get() calls for every node that has no constraints. */
    private readonly _constraintNames;
    constructor(schema: SchemaModel);
    evaluate(doc: XmlDocument, result: ValidationResult): void;
    private _walkIterative;
    private _evaluateConstraint;
    private _checkKeyref;
    private _checkDuplicates;
    private _evalSelector;
    private _findDescendants;
    private _evalField;
}
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